1. Field
Embodiments of the present invention relates to a method and system for forming a complex monolithic composite part. More particularly, the present invention relates to forming, using, and removing a mandrel to manufacture a complex monolithic composite part.
2. Related Art
Hollow composite parts are often used in the manufacture of aircrafts. A hollow composite part is typically formed using layers or plies of composite material wrapped around a mandrel having a desired shape of the hollow composite part. The composite material is then sealed within an external impermeable membrane which is compressed by removal of air in the external impermeable membrane to consolidate the composite materials. However, this compression pressure applied on the outer surfaces of the composite part does not consistently provide proper consolidation of the composite materials.
After sealing, the composite material is hardened through a curing process, after which the external impermeable membrane is removed and the mandrel is removed from within the resulting composite part. Some prior art mandrels of basic geometry slightly shrink following the curing process to allow the mandrel to be removed from within the hollow composite part. However, these shrinking mandrels can not be used within a hollow complex monolithic composite part, such as a composite part with a hollow grid shape or complex contours, because the mandrels become trapped within the composite part.
Other prior art methods of removing the mandrels use foam mandrels in the manufacture of hollow composite parts and remove the mandrel with a method called glass bead blasting. Glass bead blasting involves shooting a plurality of glass beads at high speeds into one end of the foam mandrel with a blasting apparatus that travels from one end of the foam mandrel to the other, breaking the mandrel into smaller fragments. The fragments of the foam mandrel are then suctioned out or otherwise removed from the hollow composite part. However, the impact of the glass beads during mandrel removal can damage the inner surfaces of the hollow composite part.
Accordingly, there is a need for an improved method of forming hollow composite parts that overcomes the limitations of the prior art.